1. Field of the Invention
The present invention relates to a liquid crystal display, and more particularly to, a liquid crystal display capable of preventing spots from being generated by difference in brightness of various regions of the display.
2. Discussion of Related Art
Recently, various flat panel displays (FPDs) having a lower weight and volume than cathode ray tubes (CRTs) have been developed. The FPDs include liquid crystal displays (LCDs), field emission displays (FEDs), plasma display panels (PDPs), and organic light emitting displays (OLEDs).
Among the FPDs, the LCDs are small and light and have low power consumption. Therefore, the LCDs have been in the spotlight as substitutes that can overcome the disadvantages of the conventional CRTs. Currently, the LCDs are used in large monitors and TVs as well as in portable devices such as mobile telephones and personal digital assistants (PDA). Passive matrix LCDs having low power consumption are often used for portable display devices.
FIG. 1 illustrates a conventional passive matrix LCD.
Referring to FIG. 1, the conventional passive matrix LCD includes a liquid crystal panel 2, a data driver 8 for driving data lines D1 to Dm of the liquid crystal panel 2, and a scan driver 6 for driving scan lines S1 to Sn of the liquid crystal panel 2.
The liquid crystal panel 2 includes pixels 4 positioned where the scan lines S1 to Sn and the data lines D1 to Dm cross over one another. The pixels 4 are selected when scan signals are supplied to the scan lines S1 to Sn to emit light components corresponding to data signals supplied to the data lines D1 to Dm.
The scan driver 6 sequentially supplies the scan signals to the scan lines S1 to Sn in accordance with control signals from a timing controller that is not shown.
The data driver 8 generates the data signals in accordance with the control signals from the timing controller and supplies the generated data signals to the data lines D1 to Dm in synchronization with the scan signals.
The conventional LCD is obtained by attaching an upper substrate and a lower substrate to each other. As illustrated in FIG. 2, an integrated circuit 10 is mounted on a lower substrate 12 of the LCD used for a portable device (for example, a mobile telephone). The circuits of the scan driver 6 and the data driver 8 are included in the integrated circuit 10. Therefore, the integrated circuit 10 is commonly connected to the data lines D1 to Dm and the scan lines S1 to Sn.
Pixels (not shown) are arranged in a matrix in an effective display region 20 of the lower substrate 12. The data lines D1 to Dm formed in the effective display region 20 are electrically connected to the integrated circuit 10 to receive the data signals from the integrated circuit 10. On the other hand, first pads 14 are formed on a first side of the effective display region 20 and second pads 16 are formed on a second side of the effective display region 20 opposite the first side. The first pads 14 are positioned near an upper side of the effective display region 20 and are electrically connected to the integrated circuit 10, and the second pads 16 are positioned near a lower side of the effective display region 20 and are electrically connected to the integrated circuit 10. When an upper substrate that is not shown and the lower substrate 12 are attached to each other or coupled together, the first pads 14 are electrically connected to the scan lines S1 to Sn/2 positioned in the upper part of the effective display region 20 of the upper substrate and the second pads 16 are electrically connected to the scan lines Sn/2+1 to Sn positioned in the lower part of the effective display region 20 of the upper substrate.
In the conventional LCD, the scan lines S1 to Sn and the data lines D1 to Dm are connected to the integrated circuit 10 and the effective display region 20 displays a predetermined image in response to the scan signals and the data signals supplied from the integrated circuit 10.
Dummy pads 18 are formed adjacent to the second pads 16. The dummy pads 18 are used for maintaining a gap when the upper substrate and the lower substrate 12 are attached to each other. This gap corresponds to a cell gap created by formation of liquid crystal cells between the two substrates. However, in the conventional LCD, spots are generated by difference in brightness in the parts where the dummy pads 18 are formed and/or on the boundaries between the dummy pads 18 and the second pads 16. The spots are generated by non-uniformity in the heights of the dummy pads 18 and the second pads 16 when the upper substrate and the lower substrate 12 are attached to each other.